What is SPDIF?

SPDIF audio is a digital transmission protocol developed in the 80’s and is based on the standard AES/EBU protocol used in the professional field. If at the protocol level things remained almost unchanged, Sony and Philips transformed  the more expensive professional protocol into a commercial one, this was done by changing the connectors (plugs/wiring) and some hardware specs.

 AES / EBU, S / PDIF (IEC-958)

 Cabling shileded TP 110 ohm 75 ohm coaxial or fiber
 Connector 3-pin XLR RCA, Toslink (or BNC)
 Signal level 3 .. 0.5 .. 1V 10V
 Modulation biphase-mark-code biphase-mark-code
 Max.  Resolution 24 bits 20 bits (24 bit option)

Being developed by Sony in collaboration with Philips the name is no surprise:  Sony / Philips Digital Interconnect Format, hence the acronym SPDIF. (Or, in another version – Sony Philips Digital InterFace)

And if it’s in digital format it helps me?

Audio information stored in our computer or in a CD/DVD  is natively in digital format – and to be used with our speakers have to be transformed into analog electrical signals. This conversion is done by a dedicated hardware chip named: Digital C-to-Analog converter. Conversion scales performance varies depending on the price paid on the hardware. A high-performance DAC provides minimum distortion sound and a value of SNR (Signal to noise ratio) very good.

Digital transmission of sound eliminates digital-to-analog conversion and is noiseless, ie without background noise. So, using a SPDIF connection the sound quality is directly influenced by the receiver’s specifications and audio precincts.

DAC – AKM4396VF fitted sheets Azuzen X-Fi Prelude 7.1 ( see specifications )

Digital - analog converter (DAC)


SPDIF connections are made either through an optical cable (standardized by Toshiba, hence called Toslink) or through a coaxial cable (75 ohm).

TOSLINK optical and coaxial SPDIF cable

Coaxial or Optical?

Although optical connection is generally seen as a superior, in reality there is no difference in the sound quality. Coaxial or optical, it is absolutely the same SPDIF signal, bit by bit identical to the one that is carried on a coaxial connection. One advantage of the optical fiber is that there is no practical limitations concerning the length of the cable. Coaxial connection is limited to a maximum of 10m. Another advantage is that the optical connection is immune to any electrical interference.


Motherboards with SPDIF support (first one were equipped with codec C-Media ® CMI-8738), were almost common in the late 2000’s. Otherwise, SPDIF  was already present in some much pretentious hardware as: Creative Sound Blaster AWE64 (1996), AurealVorex II( 1998) or Creative Sound Blaster Live!(1997).
Meanwhile SPDIF connection has become almost standard among base plate segments among middle and standard sound card.

Optical and coaxial SPDIF on the motherboard

And most laptops made in recent years have SPDIF output. But since SPDIF output is shared with ordinary analog and many users are not aware of its presence. Today SPDIF signal is carried out via a HDMI connection.

Laptop SPDIF

To get a connection via SPDIF output  we need a 3.5mm adapter – RCA, or an RCA jack cable for coaxial transmission.

Whether a mini-plug (3.5mm) – TOSLINK optical connection if. (Or if you already have a TOSLINK cable can buy an adapter that converts one end to form mini-plug)

Toslink mini-plug


SPDIF, Windows, and home theater your home 

With a SPDIF connection we get stereo sound in PCM (uncompressed) or 48kHz maximum compressed sound in Dolby Digital 5.1 (AC-3) or DTS 48kHz with a maximum up to 640kbs bitrate.

Since multi-channel sound format Doby Digital / DTS is present  mostly only in movies, for whatever remains, over the SPDIF connection will get just two channel Stereo sound. This problem has been solved by creating Dolby Digital Live, a techonology which allows real-time creation of an AC3 stream, and this is a good way to have 5.1 sound when playing games.

What is a receiver?

When it comes to SPDIF, a receiver is any hardware that supports this protocol. In terms of audio SPDIF compatibilty, the most popular are home theater receivers. Prices can get very far by fidelity and embedded technologies. The newest receivers are compatible with high definition sound bit/96Khz 24 or 192kHz, and tipically will receive SPDIF signals over a HDMI connection.

Once a SPDIF stream will be detected by the receiver the display will show the corresponding logo:

Dolby Digital and DTS display

Receiver Dolby Digital compatible

Another category of receivers are 5.1/6.1/7.1 systems with digital input. The best example of this is the model of the Logitech Z5500.

Logitech Z5500 featuring Dolby Digital Coaxial Optical Inputs


Von Neumann computer

von neumann

John Von Neumann has never built a computer. Neumann, a Hungarian-american mathematician, has designed a computer from a mathematical point of view. His work led to the design of digital computers from the ’50s.

Today’s computers operate in principle digital computer model envisioned in the ’40s by mathematician John von Neumann. In Neumann’s vision memory was one of the five main parts of a digital computer:

  • an input device responsible for entering data into the computer (such as a keyboard)
  • a memory for storing data and programs
  • arithmetic unit for performing calculations
    a control unit which carry out instructions and data transfer between memory and arithmetic unit
  • an output device (eg monitor)


What is firmware?

Firmware is the basic software embedded in a hardware device.

Firmware – essential software routines contained in ROM memory  of a hardware device. Firmware is always responsible for basic operations, such as starting or input / output.

We can say, without fail, that any electronic device  needs firmware to operate. Firmware range from a reduced set of instructions in simple devices such as electronic alarm from the car, to more complex instructions in the case of sophisticated equipment such as smart tvs, video players, mobile phones, cameras / video equipment, medical equipment etc.

Below we can see memory chip containing the firmware of a DVD player:

Firmware unui DVD-Player

Sometimes we need the latest version

Original firmware is serving a a product mostly over its lifetime. Sometimes, however, the need arises to replace the current firmware version with one improved. If the firmware is stored in a memory chip EEPROM or flash, the user can be rewritten using a special program.

The new version of firmware and software programming EEPROM or flash memory chip can usually be obtained from the hardware device manufacturer’s website.

Firmare upgrade de pe site-ul producatorului

Update procedure

PC procedure of the firmware update can be performed directly from Windows or may require booting the computer in DOS mode.

Rewriting the BIOS of a motherboard in Windows:

Rescriere BIOS Windows

Rewriting the BIOS of motherboards in DOS:

Rescriere BIOS

Firmware and BIOS

The BIOS of a computer, acronym that comes from the Basic Input Output System, is for a computer what is the firmware for other electronic equipment.

However, the BIOS of a PC is more than just a regular firmware because it allows us to interact with it,  while a regualr firmware is a software that has no user interface. (It is there but we do not „see” it.)

BIOS interactionare

How are read / written optical disks

One of the biggest breakthroughs in storage technology is the optical storage. The basis of this type of storage is optical phenomenon known as light reflection. 1 The fact that two objects can reflect light differently,  is used by the optical storage technology to represent a number of bits in a reflective surface.

Next is to find out some details about how data storage using optical technology. In other words, you’ll learn why an optical medium is optical, not magnetic.


Optical media stores data in a layer of photosensitive storage along a spiral track. (For a compact disc, such a track would reach a length of approximately 5 km.)

Compozitie CD

Order bits are registered on the space marked by a cross in the form of microscopic cavities or dots that are designed differently to reflect light emitted by a laser beam. A flat surface means 0 (land) and a cavity or point 1 (pit).
Points that represent bits size and the distance between them is oridinul microns. (A micron is equal to a thousandth of a millimeter – 10 -6 meters). At Micron, density of points that can be represented is hundreds of millions on an area of ​​a few square centimeters.

Comparatie CDvsDVDvsBlu-ray

The laser beam

To decode billions of points inside the data storage layer is used a laser beam.

Laser bluray

Beam verifies the absence or presence of serial microscopic cavities or points that represent bits and report the electronic signals as the absence or presence of the world. Further reading electronic unit interprets electronic signals received as bytes.

Raza laser

The advantages of optical storage

The most common optical media (CD and DVD) weighing a few grams, with a thickness of 1.2 mm and a diameter of 12 cm.

Direct access to stored information.
Any information can be found in the storage area of ​​an optical medium within measurable in milliseconds.

Improved security of data stored and long use

Optical storage media not by reading wear. In terms of handling carefully the information stored on an optical disc (quality) can be accessed for ten years.

Low price per storage megabaitul
A regular media (CD or DVD) can be purchased for a ridiculously low price, and provides a relatively large storage capacity.


Most optical storage media fall WORM storage media category – Write Once Read Many.

WORM medium that can be written once is closely related to the process of writing data, which is irreversible. Storage layer once it has been modified by writing data can not be brought to its original condition.

The fact that the stored information can not be deleted or modified should not be seen as a major disadvantage. Feature information permanently prevents accidental deletion or modification thereof.

Non-optical media Worm, rerecord called, can also be read many times but at the same time can be erased and rewritten with new information.

  1. Reflection, reflections, sf 1. Phenomenon of partial return of light, sound, radiation in the environment from which they came when they encounter a surface separating two media, reflection